The primary outcomes measures for this study are: (1) tolerability: what proportion of subjects are able to complete the study on the originally assigned treatment dosage, (2) safety: monitored by adverse event frequency, vital signs and clinical laboratory values, and (3) efficacy: change proportion of time spent in the "On" state during waking hours. Secondary outcome measures concern efficacy: (1) change in Unified Parkinson' Disease Rating Scale (UPDRS) scores and other scales occurring over the 7 weeks of the study, (2) change in the individual items of the UPDRS Part IV, (3) change in CLinical Global Impression (CGI), Schwab and England Activities of Daily Living, Digit Ordering and Beck Depression Scores, and (4) Dose-response relationship of mean change from baseline to last observed value in the percent of "On" time while awake per patient home diary. Recruitment for this study is completed. Study-wide, the final follow-up visit will be in July, 1998 and analysis will commence thereafter. The study is closed to enrollment.